PRNP and fatal familial insomnia: The prion protein (PrP), a molecule discovered by Stanley Prusiner, is involved in the transmissible spongiform encephalopathies (TSEs), such as family fatal insomnia (FFI), Creutzfeldt–Jakob disease (CJD), Gerstmann–Sträussler–Scheinker (GSS), and other pathologies [1,2].